Reverse Total Shoulder Arthroplasty Reza Omid, M.D. Assistant Professor Orthopaedic Surgery Shoulder & Elbow Reconstruction Sports Medicine Keck School of Medicine of USC

Incidence of RC Tears with Osteoarthritis 5-10%

Glenohumeral OA

Glenoid cartilage is typically spared anteriorly Wear is more pronounced posteriorly with appearance of a “biconcave glenoid”.

Where Does Glenoid Wear Occur in RCT Arthropathy

REVERSE TSA

Indications for RTSA Rotator cuff dysfunction Proximal humerus fractures Glenoid bone loss Revision TSA

Reverse TSA Predictable outcome Best TSA or Hemi is better than the best reverse Best indication is CTA Worst indication is revision arthroplasty Not a good option if good FE

REVERSE TSA Two Types: Lateralized Initial design of the 70’s but abandoned Frankle design recently Medialized Grammont design 1991 Most common design (zimmer, tornier, depuy, etc)

How Does A Reverse Work? 1) Medialization/Lateralization 2) Distalization 3) Semiconstrained

Biomechanics 1. Medialization converst the shear force to a compressive force at the baseplate/glenoid interface. 2. Distalization tensions deltoid 3. Semiconstraint nature overcomes deficient cuff

Medialization

Distalization

Constraint Under active conditions, a mismatch of 4mm was found to produce translations (1- 2mm) that most closely reproduced those observed with the original anatomy (Williams JOR 1996:14(6): ).

Constraint

Benefits of Lateralization Improved ER/IR Improved deltoid contour Less notching

Benefits of Medialization Biomechanically superior (compression force at baseplate glenoid interface)

Integra Reverse Shoulder System Central Screw Peripheral Screws Baseplate Glenosphere Humeral Insert Humeral Body Stem

Glenosphere Glenospheres made of CoCr 38mm diameter Many options to varying patient anatomy, increase ROM and prevent scapular notching –Concentric Glenosphere, 2mm Lateralized –Concentric Glenosphere, 5mm Lateralized –4mm Eccentric Glenosphere, 2mm Lateralized –4mm Eccentric Glenosphere, 5mm Lateralized –4mm Eccentric Glenosphere, Inferior Hooded 2mm Lateralized

Lateralizing the C.O.R. = increased ROM, increased internal/external, decreased scapula notching. Eccentric = ideal baseplate positioning while allowing the glenosphere to be position inferiorly and avoid scapular notching. Increases deltoid tension. Both options together + multiple humeral body heights allow us to have only one diameter Glenosphere (38mm). 21 Glenosphere Positioning

Baseplate and Screws Glenoid baseplates made of Ti with Asymmatrix porous coating –15mm length post (primary cases) –25mm length post (revision and bone grafting) length options –Curved back (convex) – anatomic shape 27mm 22mm

Central Compression Screw –5.5mm x (20-45mm) length in 5mm increments –Independent compression screw in various length adds for central compression of baseplate into glenoid Peripheral polyaxial locking screws –4.5mm x (15-55mm) length in 5mm increments –Anterior and Posterior are compression screws –Superior and Inferior are compression and then locked (Variable Angle Locking Screws) Baseplate and Screws

Reverse Body Reverse Humeral Body made of Ti with Asymmatrix porous coating 142 degree inclination angle –Decreases scapular notching versus a 155 degree inclination –Increased glenoid access Polished medial calcar to allow for tuberosity and soft tissue suture retention. Asymmatrix coating allows for good secondary fixation and allows for all press fit humeral component. Morse taper and backup screw for body to stem connection 3 body height options –Small (30mm) –Standard (35mm) –Large (40mm)

Humeral insert made of UHMWPe –Standard - +0mm, +3mm, +6mm, +9mm –Retentive - +0mm, +3mm, +6mm, +9mm »Retentive option provides more glenosphere coverage providing more stability yet increased chance for scapular notching. Humeral Stems made from Ti for press fit applications –11 sizes (6-16mm) 1mm increments Humeral Stems made from CoCr for cemented applications –5 sizes (6-14mm) 2mm increments Humeral Poly Liners & Stems

Surgical Technique

Or Humeral Preparation 142 Degree Osteotomy Stem Sizing & Trial Select Small Body

Humeral Preparation Humeral Reaming Humeral Body Trial and Inserter Reamer Body Inserter

Glenoid Preparation Or Baseplate Glenoid Wire Guide Glenosphere Glenoid Wire Guide

Glenoid Preparation Glenoid Reaming Baseplate Boss Drilling Baseplate Insertion

Baseplate Screw Fixation 5.5 Central Screw Preparation 4.5 Peripheral Screw Preparation and Locking Caps

Peripheral Reamers and Trialing

Glenosphere and Body/Stem Insertion 33

Case 60 yo RHD s/p fall

Challenge Case

Extended Peg

6 Weeks Post-Op